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There may be a warp in the Kuiper Belt, possibly caused by “Planet Y” — a Mercury-to-Earth-sized world that orbits the sun way beyond the orbit of Neptune. Is there a mysterious “Planet Y” orbiting ...

Is there a massive undiscovered planet on the outer reaches of the Solar System? The idea has been around since before the discovery of Pluto in the 1930s. Labelled as planet X, prominent astronomers ...

The spacecraft had been in hibernation for close to a year, and is set to continue operations.

See more of our trusted coverage when you search. Prefer Newsweek on Google to see more of our trusted coverage when you search. A team of astronomers believe they may have discovered a new dwarf ...